Don't get the RX 480, at least not until they fix power draw issues.
You see, PCI Express standards say that a card cannot draw more than 75 watts from the slot. If a card draws more, it may damage your motherboard. Many companies like MSI and ASROCK are currently not refunding customers whose motherboards have been damaged by the RX 480 because it's out of spec. http://www.tomshardware.com/answers/id-3111173/480-290.html
Which CPU do you have? If it's at least quad core and at least 2GHz, then I would recommend the Nvidia GeForce GTX 970 for you.